Journal articles: 'Trachybasalte'

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Juvigné, Étienne, and Bruno Bastin. "Téphrostratigraphie et palynologie de tourbes du Boréal et de l’Atlantique dans le massif Central (France)." Géographie physique et Quaternaire 49, no. 2 (November 30, 2007): 207–16. http://dx.doi.org/10.7202/033037ar.

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RÉSUMÉ La composition chimique des magmas de trois téphras que l'on trouve dans des tourbières en Auvergne a été déterminée. Elle a permis de distinguer la Téphra du Montchal (trachybasalte potassique) de celle du Montcineyre (basanite) qui sont pratiquement synchrones vers 6000 BP. La Téphra de La Taphanei (8500 BP, Boréal) est un trachyte. Deux diagrammes polliniques antérieurs font état de la présence de pollen de Tilia (Atlantique) au niveau de la Téphra de La Taphanei, voire même sous elle. Une nouvelle étude de cinq tourbières démontre : (i) que des grains de pollen isolés de Tilia ne sont pas observés dans plus de 17 % des niveaux d'âge boréal; (ii) que leur présence est plus fréquente au-dessus de la Téphra de La Taphanei; (iii) que la courbe continue de Tilia ne commence que bien au-dessus de la Téphra de La Taphanei, lorsqu'il n'y a pas de lacune dans la séquence.

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Perinelli, Cristina, Silvio Mollo, Mario Gaeta, Serena De Cristofaro, Danilo Palladino, and Piergiorgio Scarlato. "Impulsive Supply of Volatile-Rich Magmas in the Shallow Plumbing System of Mt. Etna Volcano." Minerals 8, no. 11 (October 25, 2018): 482. http://dx.doi.org/10.3390/min8110482.

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Magma dynamics at Mt. Etna volcano are frequently recognized as the result of complex crystallization regimes that, at shallow crustal levels, unexpectedly change from H2O-undersaturated to H2O-saturated conditions, due to the impulsive and irregular arrival of volatile-rich magmas from mantle depths. On this basis, we have performed hydrous crystallization experiments for a quantitative understanding of the role of H2O in the differentiation of deep-seated trachybasaltic magmas at the key pressure of the Moho transition zone. For H2O = 2.1–3.2 wt %, the original trachybasaltic composition shifts towards phonotephritic magmas never erupted during the entire volcanic activity of Mt. Etna. Conversely, for H2O = 3.8–8.2 wt %, the obtained trachybasalts and basaltic trachyandesites reproduce most of the pre-historic and historic eruptions. The comparison with previous low pressure experimental data and natural compositions from Mt. Etna provides explanation for (1) the abundant release of H2O throughout the plumbing system of the volcano during impulsive ascent of deep-seated magmas; (2) the upward acceleration of magmas feeding gas-dominated, sustained explosive eruptions; (3) the physicochemical changes of gas-fluxed magmas ponding at shallow crustal levels; and (4) the huge gas emissions measured at the summit craters and flank vents which result in a persistent volcanic gas plume.

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Karimov, Vagif M. "Some geological and petrological characteristics of the Eocene trachybasalt-trachyandesite- basalt-phonolite formation of the Talysh zone (Azerbaijan)." Journal of Geology, Geography and Geoecology 31, no. 3 (September 23, 2022): 484–92. http://dx.doi.org/10.15421/112244.

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This article discusses the stages of crystallization of the Eocene trachybasalt-tra- chyandesitebasalt-phonolith formation of the Talysh zone. Determination of the composi- tion of the primary magma, evolution and melting fraction of the initial melt of the Eocene volcanism of the Talysh zone within Azerbaijan. Eocene volcanism of the trachybasalt-tra-chyandesitebasalt-phonolith formation of the Talysh zone. Petrographic, petrochemical, geochemical studies of rocks, typomorphic features of mineral paragenesis, chemical composition of rocks were carried out by X-ray spectral and X-ray fluorescence analysis. The analyzes of the conducted studies show that the Talysh zone was formed in the Eocene time. Stages of evolution of the original magma and typomorphic features of mineral parageneses have been established. The distributions of microelements in mineral parageneses, which are direct participants in the crystallization processes that took place in intermediate chambers at different depths, have been studied. At present, the question arises of the need to clarify the typomorphic features of igneous complexes, as factors that determine the geodynamic regimes of their formation, and to determine the potential ore content. The petrographic and petrochemical characteristics of the volcanic rocks are given. It was found that if the process of differentiation in the Early-Middle Eocene was more distinct with the initial formation of more magnesian rock varieties (picrite-trachybasalts), and subsequently more ferruginous ones (trachyandesites and trachyandesitebasalts), then such accumulation of iron is not observed in porphyritic trachyandesites. This petrochemical feature is obviously associated with the duration of the break in volcanism, caused by the formation of a thick sedimentary-tuffaceous stratum, accompanied by the initiation and manifestation of an intermediate chamber of medium composition. Volcanism in the Late Eocene was undifferentiated and was not accompanied by the formation of medium differences. The appearance in the late Eocene of leucite phonolites, which represent an alkaline branch, and the absence of transitional varieties indicate the autonomous development of vit- robasalts and leucite phonolites. It is concluded that from the early phases of the manifestation of Eocene volcanism to the later phases, the change in the material composition along the lateral is expressed in the manifestation of more alkaline facies with a significant predominance of K over Na and with a greater correspondence to the differentials of the shoshonite series.

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Krasnobaev, Artur A., Victor N. Puchkov, Nina D. Sergeeva, and Sofia V. Busharina. "Polychronous zircons of volcanics of the Navysh complex of the Lower Riphean Ai Formation (Southern Urals)." Georesursy 22, no. 4 (December 2020): 101–12. http://dx.doi.org/10.18599/grs.2020.4.101-112.

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The volcanics of the Navysh complex of the Lower Riphean Ai Formation in the Southern Urals are well studied petrochemically and dated by several methods. In 2013 zircons from a trachybasalt porphyrite (sample 2152) gave a concordant SHRIMP date 1752±11 Ma, which was used as a fundamental for the lower boundary of the Riphean with no special arguments against it. The later attempts to repeat this date for the Navysh volcanics were not successful: the collected zircons were either more ancient (> 2500 Ma), or more young (< 500 Ma). From the beginning, the zircons with such ages were regarded as xenogenic or secondary metasomatic, or belonging to paleozoic dykes intruding the Riphean volcanics. However, the clearly expressed mineralogical properties of the Paleozoic zircons and their frequent presence in volcanics, not dykes, led to a conclusion that the zircons and Navysh volcanics, containing them, and exposed within the area of development of the Ai Formation, are polychronous. To support this conclusion, the authors studied in more detail the zircons of the Navysh trachybasalts, developed in the Ai Formation. The main conclusion, obtained from this new data, was that the volcanics attributed to the Navysh complex, form a polychronous system, including both the Lower Riphean (1750 Ma) and Paleozoic (450 Ma) rocks. The zircons of these age groups differ in their mineralogical and geochemical properties supporting the idea that they belong to different primary sources which may be due to repeating plume processes, which partly reanimated – heated and melted-rocks of the previous cycle and/or created new sources of melts.

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Babayeva, Gultekin J. "Petrological-mineralogical evolutional transformation of Cretaceous teschenite-tephrite, syenite-trachyte, and essexite-trachybasalt primary meltings (Carpathian, Caucasian and North TransBaikal regions)." Journal of Geology, Geography and Geoecology 32, no. 3 (September 25, 2023): 450–60. http://dx.doi.org/10.15421/112340.

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This article discusses spatial and time distribution of Cretaceous teschenite-tephrite and essexite-trachybasalt complexes of the Carpathian, Caucasian, North TransBaikal regions. The main aim of the article is a comparative analysis of petrological-mineralogical features of similar complexes located in the Carpathians, North Caucasus and Transbaikal, Georgia in the Khojavand depression in the southeast of the Lesser Caucasus. Rocks of teschenite-tephrite, essexite-trachybasalt complexes were formed in the Cretaceous, early Eocene and Miocene. The differentiates of the considered complexes are localized in graben-like structures. The initial stage of graben formation is associated with the formation of rocks of the essexite-trachybasalt complex. The next stage of this process is associated with the formation of the teschenite-tephrite complex. According to stages of bedding and develop- ment of riftogenic graben structures, the essexite-trachybasalt complex formed first, at a mature stage – teschenite-tephrite one. At the initial stage high titanian olivine subalkaline basaltic melting occurred from the garnet-phlogopite lherzolite substratum. At the second stage – subalkaline picrite melting occurred from this substratum, which is primary for teschenite-tephrite and syenite-trachyte com- plexes. The metasomatized high-titanium phlogopite lherzolite substrate was subjected to melting twice. An earlier stage of melting of the substrate did not exceed 0.1%, from which a high-titanium olivine trachybasalt melt was separated. The second stage of melting of the substrate reached 10-12%. In this case, a subalkaline olivine picrite melt was formed. Evolution of primary meltings occurred in different-depth intermediate foci and intrusive chambers. The main factor in evolution along with controlling geodynamic regime was gravitational-crystallized differentiation. The identified mineral parageneses, starting from the early stage of the evolution of the subalkaline picrite melt to the late one, actually characterize the stages of crystallization of the noted melt in the intrusive chamber and intermediate chambers. The Eocene and Miocene teschenite-tephrite and essexite-trachybasalt complexes are characterized by a smaller areal distribution and petrographic diversity. Obviously, during this period, the intense activation of transverse magma-feeding faults contributed to the rapid uplift of the subalkaline picrite melt into the upper horizons of the earth’s crust.

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MAALOE, S., I. SORENSEN, and J. HERTOGEN. "The Trachybasaltic Suite of Jan Mayen." Journal of Petrology 27, no. 2 (April 1, 1986): 439–66. http://dx.doi.org/10.1093/petrology/27.2.439.

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Yea, Nam Hee, Sung-Hyo Yun, and Jeong Seon Koh. "Plagioclase Composition of Feldspar Trachybasalt in Jeju Island." Journal of the Petrological Society of Korea 21, no. 3 (September 30, 2012): 309–33. http://dx.doi.org/10.7854/jpsk.2012.21.3.309.

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Lipman, Peter W., and Matthew J. Zimmerer. "Magmato-tectonic links: Ignimbrite calderas, regional dike swarms, and the transition from arc to rift in the Southern Rocky Mountains." Geosphere 15, no. 6 (September 30, 2019): 1893–926. http://dx.doi.org/10.1130/ges02068.1.

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Abstract Radial and linear dike swarms in the eroded roots of volcanoes and along rift zones are sensitive structural indicators of conduit and eruption geometry that can record regional paleostress orientations. Compositionally diverse dikes and larger intrusions that radiate westward from the polycyclic Platoro caldera complex in the Southern Rocky Mountain volcanic field (southwestern United States) merge in structural trend, composition, and age with the enormous but little-studied Dulce swarm of trachybasaltic dikes that continue southwest and south for ∼125 km along the eastern margin of the Colorado Plateau from southern Colorado into northern New Mexico. Some Dulce dikes, though only 1–2 m thick, are traceable for 20 km. More than 200 dikes of the Platoro-Dulce swarm are depicted on regional maps, but only a few compositions and ages have been published previously, and relations to Platoro caldera have not been evaluated. Despite complications from deuteric alteration, bulk compositions of Platoro-Dulce dikes (105 new X-ray fluorescence and inductively coupled plasma mass spectrometry analyses) become more mafic and alkalic with distance from the caldera. Fifty-eight (58) new 40Ar/39Ar ages provide insight into the timing of dike emplacement in relation to evolution of Platoro caldera (source of six regional ignimbrites between 30.3 and 28.8 Ma). The majority of Dulce dikes were emplaced during a brief period (26.5–25.0 Ma) of postcaldera magmatism. Some northeast-trending dikes yield ages as old as 27.5 Ma, and the northernmost north-trending dikes have younger ages (20.1–18.6 Ma). In contrast to high-K lamprophyres farther west on the Colorado Plateau, the Dulce dikes are trachybasalts that contain only anhydrous phenocrysts (clinopyroxene, olivine). Dikes radial to Platoro caldera range from pyroxene- and hornblende-bearing andesite to sanidine dacite, mostly more silicic than trachybasalts of the Dulce swarm. Some distal andesite dikes have ages (31.2–30.4 Ma) similar to those of late precaldera lavas; ages of other proximal dikes (29.2–27.5 Ma) are akin to those of caldera-filling lavas and the oldest Dulce dikes. The largest radial dikes are dacites that have yet younger sanidine 40Ar/39Ar ages (26.5–26.4 Ma), similar to those of the main Dulce swarm. The older andesitic dikes and precaldera lavas record the inception of a long-lived upper-crustal magmatic locus at Platoro. This system peaked in magmatic output during ignimbrite eruptions but remained intermittently active for at least an additional 9 m.y. Platoro magmatism began to decline at ca. 26 Ma, concurrent with initial basaltic volcanism and regional extension along the Rio Grande rift, but no basalt is known to have erupted proximal to Platoro caldera prior to ca. 20 Ma, just as silicic activity terminated at this magmatic locus. The large numbers and lengths of the radial andesitic-dacitic dikes, in comparison to the absence of similar features at other calderas of the San Juan volcanic locus, may reflect location of the Platoro system peripheral to the main upper-crustal San Juan batholith recorded by gravity data, as well as its proximity to the axis of early rifting. Spatial, temporal, and genetic links between Platoro radial dikes and the linear Dulce swarm suggest that they represent an interconnected regional-scale magmatic suite related to prolonged assembly and solidification of an arc-related subcaldera batholith concurrently with a transition to regional extension. Emplacement of such widespread dikes during the late evolution of a subcaldera batholith could generate earthquakes and trigger dispersed small eruptions. Such events would constitute little-appreciated magmato-tectonic hazards near dormant calderas such as Valles, Long Valley, or Yellowstone (western USA).

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Hafidhah Nurul Haq, Mega Fatimah Rosana, Cipta Endyana, Katon Sena Ajie Nugraha, and Irpan Alamsyah. "Geochemistry of Igneous Rocks of Citirem Formation and Its Implications for the Tectonic Setting in Ciletuh – Palabuhanratu UNESCO Global Geopark Area." Journal of Geoscience, Engineering, Environment, and Technology 9, no. 1 (March 28, 2024): 58–68. http://dx.doi.org/10.25299/jgeet.2024.9.1.14367.

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The igneous rocks of the Citirem Formation in the Ciletuh – Palabuhanratu UNESCO Global Geopark area petrographically not only consist of basalt, but also andesite, dacite, and gabbro. The characteristics of basalts Citirem Formation are composed of plagioclase 43% – 58% and olivine, mostly have amygdaloidal and aphanitic textures. Andesites are composed of 45% – 65% plagioclase, absence of olivine, mostly aphanitic and trachytic, some have intergranular textures. Dacite comprises 50% plagioclase, 20% quartz, and the absence of olivine, and aphanitic, intersertal textures. Gabbros are composed of 62% plagioclase, 6% – 12% olivine, with phaneritic texture. Based on the plot of the major elements vs SiO2 diagram, MgO, FeOt (Fe2O3+FeO), CaO, and TiO2 show a negative correlation with SiO2. In comparison, Na2O and K2O show a positive correlation with SiO2. The lithology of igneous rocks of Citirem Formation are basalt, trachybasalt, basaltic trachyandesite, trachyandesite, andesite, dacite and gabbro based on a plot of the Na2O+K2O vs SiO2 diagram for volcanic and plutonic rocks. The origin of magma type can be distinguished based on the plot of K2O vs SiO2 diagrams, the igneous rocks of Citirem Formation are divided into low-K, medium-K, high-K, and shoshonite magma series. Dacite STA 2, andesite STA 7, basaltic andesite STA 8, trachyandesite STA 10 and gabbro STA 14 are calc-alkaline based on triangular diagram Th-Hf-Ta-Zr-Nb. Gabbro STA 17 indicates IAT (island arc tholeiite), trachybasalt STA 19, basalt STA 20 and basaltic trachyandesite STA 27 are E-MORB, WPT (within plate tholeiitic), In contrast, trachybasalt STA 28 is WPA (within plate alkali). Primitive mantle long, NMORB-normalized REE patterns and chondrites-normalized show some rocks have distinctive patterns that have similarities with suprasubduction zone ophiolite rocks, MORB of Mirdita ophiolite, and some show similarities with patterns from OIB and E-MORB.

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Wen-Ge, Zhou, Xie Hong-Sen, Zhao Zhi-Dan, and Guo Jie. "Garnet Growth in the Early Stage of Trachybasalt-Eclogite Transformation." Chinese Physics Letters 18, no. 11 (October 10, 2001): 1500–1503. http://dx.doi.org/10.1088/0256-307x/18/11/324.

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Loock, Sébastien, Benjamin van Wyk de Vries, and Jean-Marc Hénot. "Clinker formation in basaltic and trachybasaltic lava flows." Bulletin of Volcanology 72, no. 7 (April 10, 2010): 859–70. http://dx.doi.org/10.1007/s00445-010-0362-y.

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Kadyrova, Z. R., I. K. Shokosimov, and M. N. Kazakova. "Establishment of the iron-containing phase of the gavasaia porphyrite by the method of mössbauer spectroscopy for obtaining basalt fibers." NOVYE OGNEUPORY (NEW REFRACTORIES), no. 6 (November 30, 2023): 3–7. http://dx.doi.org/10.17073/1683-4518-2023-6-3-7.

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The results of studies on the determination of the iron-bearing phase of trachybasalt porphyrite of the Karabulak site of the Gavasay deposit of Uzbekistan and their suitability for obtaining basalt fiber by the method of Mössbauer spectroscopy are presented. It has been established that on the basis of this igneous rock it is possible to obtain a continuous basalt fiber without corrective additives for heat-insulating materials.

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Demir, Sinan, Pelin Alaboz, Orhan Dengiz, Hüseyin Şenol, Kamil Yilmaz, and Oğuz Başkan. "Physico-chemical and mineralogical changes of lithic xerorthent soils on volcanic rocks under semi-arid ecological conditions." Earth Sciences Research Journal 26, no. 4 (February 28, 2023): 291–301. http://dx.doi.org/10.15446/esrj.v26n4.96571.

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This study investigates the mineralogical changes and soil development processes of young soils formed on various bedrocks of volcanic origin under the same land use/land cover and climate conditions. The current study was conducted in Lithic Xerorthent soils formed on tuff, trachybasalt, and trachyandesite bedrock between Sandıklı-Şuhut districts of Afyonkarahisar. The three soil profiles excavated in the study area were classified in Entisols order based on Soil taxonomy. The primary minerals, sanidine and muscovite, and the clay minerals, smectite, kaolinite, and illite, were widely determined in three soil profiles which were named Profile I (PI), Profile II (PII), and Profile III (PIII). According to the chemical alteration index (CIA) values, which indicate weathering, the soils formed on the tuff bedrock were slightly weathered (77.04%). The chemical weathering index (CIW) in the soils' surface horizons formed on the trachybasalt and trachyandesite bedrock are classified as non-weathering rocks with 24.43% and 33.88%. Basic cations are found at high levels in the tuff bedrock. The determination of phillipsite, gismondin and calcite minerals is an indication that the mineral content of the bedrock and the bedrocks have a significant effect on soil formation. The relationship between the bedrock and the soil has been revealed. As a result of the study, it was concluded that there were significant differences in their physico-chemical characteristics, weathering rates, and mineralogical properties. However, they were characterized as young soils since they do not contain any subsurface diagnostic horizons on the volcanic bedrock under the same climatic and land use/land cover conditions.

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Ripa, Magnus, and Michael B. Stephens. "Chapter 9 Continental magmatic arc and siliciclastic sedimentation in the far-field part of a 1.7 Ga accretionary orogen." Geological Society, London, Memoirs 50, no. 1 (2020): 253–68. http://dx.doi.org/10.1144/m50-2017-3.

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AbstractTrachyandesitic to trachybasaltic lavas, interlayered siliciclastic sedimentary rocks and subaerial ignimbrites with a rhyolitic to trachydacitic composition lie unconformably above metamorphic rocks in west-central Sweden. These volcanic rocks erupted at 1711 + 7/−6 to 1691 ± 5 Ma and belong to a high-K, calc-alkaline to shoshonitic suite deposited in a continental arc setting. Positive ɛNd values and Nb/Yb ratios in the trachyandesitic to trachybasaltic rocks indicate an enriched mantle source. Coeval, 1710 ± 11 to 1681 ± 16 Ma plutonic and subvolcanic rocks are mainly granitic or quartz syenitic in composition. Subordinate components include quartz monzonite, quartz monzodiorite and monzogabbro or gabbro. ɛNd values in the range −1.0 to + 1.1 overlap with those in the inferred 1.9–1.8 Ga source rocks. All these rocks belong to the youngest phase of the lithodemic unit referred to as the Transscandinavian Igneous Belt. This magmatic province extends in a roughly NNW direction for at least 900 km, variably deformed and metamorphosed equivalents occurring inside and beneath younger orogenic belts to the south (Sveconorwegian) and north (Caledonian). The part of the province in west-central Sweden addressed here represents a far-field and shallow crustal component in this 1.7 Ga accretionary orogenic system.

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Kadyrova, Z. R., I. K. Shokosimov, and M. N. Kazakova. "DETERMINATION OF THE CHEMICAL AND MINERALOGICAL COMPOSITION OF TRACHIBASALTIC PORPHIRITE FROM THE GAVASAY FOR OBTAINING MINERAL FIBER." Steklo i Keramika, no. 20 (August 2023): 56–61. http://dx.doi.org/10.14489/glc.2023.08.pp.056-061.

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The results of studies of the chemical and mineralogical compositions and the main characteristics for determining the suitability of trachybasaltic porphyrite from the Gavasay deposit of Uzbekistan for obtaining heat-insulating material, in particular mineral fiber, are presented. It has been established that this new deposit of igneous rock can be used as the main raw material component for the production of basalt fiber products, a widely demanded and modern material in the construction industry.

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Gomes, Celso De Barros, Ana Maria Castillo Clerici Clerici, Victor Velázquez Fernandez, Angelo De Min, and Piero Comin‑Chiaramonti. "The dykes in the western fringe of the Ybytyruzú Hills, central‑eastern Paraguay region." Geologia USP. Série Científica 17, no. 2 (August 1, 2017): 131. http://dx.doi.org/10.11606/issn.2316-9095.v17-121977.

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The Cordillera del Ybytyruzú region of central eastern Paraguay is predominantly formed by tholeiitic lava flows from the Early Cretaceous age (130–134 Ma) cut by K alkaline dykes and intrusive bodies aged between 125 and 127 Ma. Petrochemical studies focusing on 14 samples of dykes from the region show an apparent affinity to Roman Province Type rocks and total consistency with the overall petrographic association of the Asunción Sapucai Villarrica (ASV) graben. Two main potassic suites are distinguished: B P (basanite tephrite phonotephrite phonolite) and AB T (alkali basalt trachybasalt trachyandesite trachyphonolite/trachyte).The occurrence of lamproitic rocks in the area has so far not been confirmed.

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Orlando, Andrea D'Orazio, Pietro Armienti, and Daniele Borrini. "Experimental determination of plagioclase and clinopyroxene crystal growth rates in an anhydrous trachybasalt from Mt Etna (Italy)." European Journal of Mineralogy 20, no. 4 (August 29, 2008): 653–64. http://dx.doi.org/10.1127/0935-1221/2008/0020-1841.

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Dabiri, Rahim, Mohamad Emami, Habib Mollaei, Bin Chen, Mansor Abedini, Nematallah Omran, and Mitra Ghaffari. "Quaternary post-collision alkaline volcanism NW of Ahar (NW Iran): geochemical constraints of fractional crystallization process." Geologica Carpathica 62, no. 6 (December 1, 2011): 547–62. http://dx.doi.org/10.2478/v10096-011-0039-2.

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Quaternary post-collision alkaline volcanism NW of Ahar (NW Iran): geochemical constraints of fractional crystallization process Major and trace elements and Sr-Nd isotopic data are presented for the Quaternary alkaline volcanism NW of Ahar (NW Iran). The exposed rocks mainly consist of alkali basalts, trachybasalts, basaltic trachyandesites and trachyandesites. Alkali basalts and trachybasalts display microlithic porphyritic texture with phenocrysts of olivine, clinopyroxene, and plagioclase in microlithic groundmass. In the more evolved rocks (basaltic trachyandesites and trachyandesites), amphibole and biotite have appeared. Major and trace element abundances vary along continuous trends of decreasing MgO, TiO2, Fe2O3*, CaO, Co, Cr, V and Zn, and increasing K2O, Al2O3, Ba and Th with increasing SiO2. The Sr and Nd isotopic ratios vary from 0.704463 to 0.704921 and from 0.512649 to 0.512774, respectively. Alkali basalts with high 143Nd/144Nd ratio, low 87Sr/86Sr ratio and high MgO, Ni and Cr contents indicate that they were generated from relatively primitive magmas. Ba, Cr and La/Sm ratios versus Rb suggest that fractional crystallization of alkali basalts could have played a significant role in the formation of evolved rocks. Assimilation and fractional crystallization modelling, as well as Rb/Zr, Th/Yb and Ta/Yb ratios clearly indicate that crustal contamination accompanied by the fractional crystallization played an important role in petrogenesis of the trachyandesites. The small compositional differences between magma types, isotopic composition, mineralogy and nonlinear trends on Harker diagrams also indicate that magma mixing was not an essential process in the evolution of the Ahar magmas. Petrogenetic modelling has been used to constrain sources. Trace element ratio plots and REE modelling indicate that the alkali basalts were generated from a spinel-peridotite source via small degrees (~2.5%) of fractional melting.

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Holm, Paul Martin, L. E. Pedersen,, and B. Højsteen. "Geochemistry and petrology of mafic Proterozoic and Permian dykes on Bornholm, Denmark: Four Episodes of magmatism on the margin of the Baltic Shield." Bulletin of the Geological Society of Denmark 58 (May 17, 2010): 35–65. http://dx.doi.org/10.37570/bgsd-2010-58-04.

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More than 250 dykes cut the mid Proterozoic basement gneisses and granites of Bornholm. Most trend between NNW and NNE, whereas a few trend NE and NW. Field, geochemical and petrological evidence suggest that the dyke intrusions occurred as four distinct events at around 1326 Ma (Kelseaa dyke), 1220 Ma (narrow dykes), 950 Ma (Kaas and Listed dykes), and 300 Ma (NW-trending dykes), respectively. The largest dyke at Kelseaa (60 m wide) and some related dykes are primitive olivine tholeiites, one of which has N-type MORB geochemical features; all are crustally contaminated. The Kelseaa type magmas were derived at shallow depth from a fluid-enriched, relatively depleted, mantle source,but some have a component derived from mantle with residual garnet. They are suggested to have formed in a back-arc environment. The more than 200 narrow dykes are olivine tholeiites (some picritic), alkali basalts, trachybasalts, basanites and a few phonotephrites. The magmas evolved by olivine and olivine + clinopyroxene fractionation. They have trace element characteristics which can be described mainly by mixing of two components: one is a typical OIB-magma (La/Nb < 1, Zr/Nb = 4, Sr/Nd = 16) and rather shallowly derived from spinel peridotite; the other is enriched in Sr and has La/Nb = 1.0 - 1.5, Zr/Nb = 9, Sr/Nd = 30 and was derived at greater depth, probably from a pyroxenitic source. Both sources were probably recycled material in a mantle plume. A few of these dykes are much more enriched in incompatible elements and were derived from garnet peridotite by a small degree of partial melting. The Kaas and Listed dykes (20-40 m) and related dykes are evolved trachybasalts to basaltic trachyandesites. They are most likely related to the Blekinge Dalarne Dolerite Group. The few NW-trending dykes are quartz tholeiites, which were generated by large degrees of rather shallow melting of an enriched mantle source more enriched than the source of the older Bornholm dykes. The source of the NW-trending dykes was probably a very hot mantle plume.

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Leat, P. T., and R. S. Thorpe. "Geochemistry of an ordovician basalt-trachybasalt-subalkaline/peralkaline rhyolite association from the Lleyn Peninsula, North Wales, U.K." Geological Journal 21, no. 1 (January 1986): 29–43. http://dx.doi.org/10.1002/gj.3350210103.

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21

Saputro, Sugeng Purwo, Dwi Ratih Purwaningsih, and Bambang Priadi. "Peralihan Rezim Tektonik: Implikasinya pada Konsentrasi Torium di Mamasa dan Tana Toraja, Sulawesi-Indonesia." EKSPLORIUM 41, no. 2 (November 30, 2020): 87. http://dx.doi.org/10.17146/eksplorium.2020.41.2.6063.

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ABSTRAK Mamasa dan Tana Toraja secara geografis merupakan bagian dari lengan barat Pulau Sulawesi. Batuan-batuan mafik di daerah tersebut dan sekitarnya memiliki nilai laju radiasi tinggi dan anomali kandungan torium (Th). Penelitian ini bertujuan untuk mengetahui mekanisme tataan tektonik yang berperan dalam peningkatan konsentrasi Th. Enam sampel batuan dianalisis menggunakan analisis petrografi dan geokimia (AAS, ICP-MS, NA, dan XRF), dilengkapi dengan pentarikhan umur menggunakan metode 40K-40Ar pada sampel batuan terpilih. Pengamatan petrografi memperlihatkan kehadiran mineral plagioklas, olivin, piroksen, hornblenda, nefelin, dan alanit pada batuan yang diidentifikasi sebagai nefelin-basanit, basalt, trakhibasalt, dan gabro. Sejumlah tekstur yang tampak pada batuan tersebut mengindikasikan kontaminasi dan perubahan kondisi tektonik. Analisis geokimia menunjukkan bahwa nefelin-basanit, basalt, trakhibasalt, dan gabro (absarokit) terbentuk pada batas kontinental aktif (ACM) yang sedang mengalami transisi dari subduksi aktif (penunjaman ke arah barat) menjadi post-subduksi. Perubahan tataan tektonik membuat magma membeku pada kondisi yang sangat ekstrim. Proses pembekuan magma diinterpretasikan terjadi pada umur sekitar 13,10-11,02 Ma. Mekanisme tersebut berperan penting terhadap terjadinya peningkatan konsentrasi torium di Mamasa dan Tana Toraja.ABSTRACT Mamasa and Tana Toraja geographically are part of the western arm of Sulawesi Island. The mafic rocks in these areas and their surroundings have high radiation dose rate and thorium (Th) anomaly content. This research aim is to determine tectonic setting mechanism which play the important role on the increasing of Th concentration. Six rock samples were analysed using petrography and geochemical analyses (AAS, ICP-MS, NA, and XRF) completed with the 40K-40Ar dating on selected rock samples. Petrography observations show plagioclase, olivine, pyroxene, hornblende, nepheline, and allanite minerals presence in the rocks which identified as nepheline-basanite, basalt, trachybasalt, and gabbro. Numbers of texture appearances in the rocks indicate contamination and changes on tectonic setting. Geochemistry analysis shows that nepheline-basanite, basalt, trachybasalt, and gabbro (absarokite) were formed at the active continental margin (ACM), which is undergoing active subduction (westward subduction) to post-subduction transition. The changing of tectonic setting made magma solidify in extreme conditions. The magma solidify process is interpreted to occur at the age of 13.10-11.02 Ma. These mechanisms play an important role for the increase of thorium concentration in Mamasa and Tana Toraja.

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Togo, Abondou, Nkouandou Oumarou Faarouk, Zangmo Tefogoum Ghislain, Fagny Mefire Aminatou, Daouda Dawai, Dinamou Appoliaire, Guihdama Dagwai Justin, and Adama Haman. "Petrography and geochemical framework of guÃ©bakÃ© dolerites dyke swarms (north Cameroon, central Africa)." International Journal of Advanced Geosciences 10, no. 1 (April 5, 2022): 19–27. http://dx.doi.org/10.14419/ijag.v10i1.31939.

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Dolerites dykes of 4.5 to 25 m wide extend from 200m to 1km, crosscut the GuÃ©bakÃ© granitoids basement in northern Cameroon along EW to N100E directions. Petrographic studies reveal the microlitic porphyritic texture to classical doleritic texture of ophitic to sub-ophitic types. GuÃ©bakÃ© dolerites are mainly composed in various proportions of skeletal plagioclase and feldspar, clinopyxene, amphibole and oxides crystals. ICP-MS and ICP-AES geochemical analyses have distiguished a lava series composed of trachybasalts, basaltic trachyandesites, trachyandesites, trachytes and rhyolites of continentale tholeiites affinity. Lavas have been differenciated trough fractional crystallization process coupled with crustal contamination and metasomatism. GuÃ©bakÃ© dolerites are products of relatively high partial melting rate of E-MORB mantle component. They stand as fingerprints of the post pan African crustal consolidation and precursor of the development of central African rift system at Cretaceous times.Â Â

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23

Williams-Jones, Glyn, René W. Barendregt, James K. Russell, Yannick Le Moigne, Randolph J. Enkin, and Rose Gallo. "The age of the Tseax volcanic eruption, British Columbia, Canada." Canadian Journal of Earth Sciences 57, no. 10 (October 2020): 1238–53. http://dx.doi.org/10.1139/cjes-2019-0240.

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A recent volcanic eruption occurred at Tseax volcano that formed a series of tephra cones in northwestern British Columbia, Canada. The explosive to effusive eruption also formed a 32 km long sequence of Fe-rich Mg-poor basanite–trachybasalt lavas covering ∼40 km2. Oral histories of the Nisg_a’a Nation report that the eruption may have caused as many as 2000 fatalities. The actual eruption date and question of whether there was one or multiple eruptive episodes in the 14th and 18th centuries are, as of yet, unresolved. New radiocarbon dating of wood charcoal from immediately beneath vent-proximal tephra deposits and complementary age information suggest an eruption in 1675–1778 CE (95.4% probability) was responsible for the formation of the tephra cone. New paleomagnetic and geochemical data from the tephra cone and lava flows suggest there is, in fact, no statistically significant difference in time between the explosive and effusive deposits and that they formed during a single eruptive episode.

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Mollo, S., J. D. Blundy, G. Iezzi, P. Scarlato, and A. Langone. "The partitioning of trace elements between clinopyroxene and trachybasaltic melt during rapid cooling and crystal growth." Contributions to Mineralogy and Petrology 166, no. 6 (October 16, 2013): 1633–54. http://dx.doi.org/10.1007/s00410-013-0946-6.

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25

Peretyazhko, I. S., E. A. Savina, and S. I. Dril’. "Early Cretaceous trachybasalt-trachyte-trachyrhyolitic volcanism in the Nyalga basin (Central Mongolia): sources and evolution of continental rift magmas." Russian Geology and Geophysics 59, no. 12 (December 2018): 1679–701. http://dx.doi.org/10.1016/j.rgg.2018.12.011.

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26

Giorgetti, Giovanna, Thomas Monecke, Reinhard Kleeberg, and Mark D. Hannington. "Low-temperature hydrothermal alteration of trachybasalt at Conical Seamount, Papua New Guinea: formation of smectite and metastable precursor phases." Clays and Clay Minerals 57, no. 6 (December 1, 2009): 725–41. http://dx.doi.org/10.1346/ccmn.2009.0570606.

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27

Zhou, Wenge, Hongsen Xie, Zhidan Zhao, Weiguo Zhu, Jie Guo, and Ji’an Xu. "The effect of phase transition on the compressional wave velocity for a trachybasalt at high temperature and high pressure." Chinese Science Bulletin 44, no. 15 (August 1999): 1415–18. http://dx.doi.org/10.1007/bf02885995.

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28

Terekhov, E. N., A. B. Makeyev, S. G. Skublov, O. I. Okina, and Yu A. Maximova. "Quartz Porphyries of the Outer Islands of the Gulf of Finland ‒ Volcanic Comagmates of the Rapakivi Granites." Вулканология и сейсмология 17, no. 6 (November 1, 2023): 101–21. http://dx.doi.org/10.31857/s020303062370030x.

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The article presents new petrogeochemical data of rocks from the area of the Outer Islands of the Gulf of Finland. Previously, quartz porphyries of Gogland Island were considered as a standard of volcanic comagmates of Rapakivi granite of the Vyborg massif. There are two effusive tolshas on Sommers Island. The “Southern” is composed of quartz porphyries, with an isotopic age of 1.66 Ga old, so they can be considered as the earliest manifestations of Riphean magmatic activity in this area. In addition to quartz porphyries, trachybasalts, andesibasalts, and dacites are present in the “Northern” strata, and its isotopic age is 1.59‒1.57 Ga old, which does not correspond to the values of the nearby Vyborg massif 1.65‒1.63 Ga old. Therefore, despite the pro-ximity of the compositions of quartz porphyry and rapakivi granites, volcanites are not products of differentiation of the magma initial for granites, but were formed independently of them from the same type of source, but in a slightly different structural environment, allowing their free flow to the Earth’s surface.

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29

Demonterova, E. I., A. V. Ivanov, S. V. Palessky, V. F. Posokhov, N. S. Karmanov, and L. A. Pel’gunova. "Feldspar Megacrysts as a Source of Information on Crustal Contamination of Basaltic Melt." Геохимия 68, no. 7 (July 1, 2023): 651–68. http://dx.doi.org/10.31857/s0016752523070026.

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The paper discusses data on the elemental composition and 87Sr/86Sr, and δ18O isotopic ratios of feldspar megacrysts collected from lava flows, tuffs, and cinders of three volcanic fields in the Baikal rift system: Iya–Uda, Vitim, and Khamar-Daban, which are located within the early Precambrian, Riphean, and Paleozoic crustal blocks, respectively. Megacrysts are hosted in trachybasalts in the Iya–Uda and Khamar-Daban fields and in basanites in the Vitim field. Megacrysts belong to the following three compositional groups of minerals: (i) plagioclase in lavas of the Iya–Uda field, (ii) anorthoclase in lava flows, tuffs, and cinders of the Khamar-Daban and Vitim fields, and (iii) sanidine in the Vitim field. Elemental and isotope data suggest that megacrysts crystallized in volcanic chambers at different depth levels: anorthoclase crystallized from the most primitive magma with mantle-derived isotopic signatures at subcrustal depth levels, plagioclases were produced in deep crustal chambers during the interaction between mantle-derived magma and crustal rocks, and sanidine was captured from the upper crustal rocks.

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30

Moon, Inkyeong, Hyunwoo Lee, Jonguk Kim, Jihye Oh, Donghoon Seoung, Chang Hwan Kim, Chan Hong Park, and Insung Lee. "Ti-Magnetite Crystallization in Melt Inclusions of Trachytic Rocks from the Dokdo and Ulleung Islands, South Korea: Implications for Hydrous and Oxidized Magmatism." Minerals 10, no. 7 (July 20, 2020): 644. http://dx.doi.org/10.3390/min10070644.

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The Dokdo and Ulleung islands (Korea) are volcanic islands in the East Sea (Sea of Japan), formed in the late Cenozoic. These volcanic islands, in the back-arc basin of the Japanese archipelago, provide important information about magma characteristics in the eastern margin of the Eurasian plate. The origin of the Dokdo and Ulleung intraplate volcanism is still controversial, and the role of fluids, especially water, in the magmatism is poorly understood. Here, we comprehensively analyzed the melt inclusions (10–100 m in diameter) hosted in clinopyroxene phenocrysts of trachyte, trachyandesite, and trachybasalt. In particular, we observed Ti-magnetite and amphibole which were crystallized as daughter mineral phases within melt inclusions, suggesting that Ti-magnetite was formed in an oxidized condition due to H2O dissociation and H2 diffusion. The Ti-magnetite exhibited compositional heterogeneities of MgO (average of 8.28 wt %), Al2O3 (average of 8.68 wt %), and TiO2 (average of 8.04 wt %). The positive correlation of TiO2 with Cr2O3 is probably attributed to evolutionary Fe–Ti-rich parent magma. Correspondingly, our results suggested hydrous and oxidized magmatism for the Dokdo and Ulleung volcanic islands.

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31

Kislov, Evgeniy V., Anna V. Aseeva, Vladislav V. Vanteev, Anton Yurievich Sinyov, and Olga A. Eliseeva. "Naryn-Gol Creek Sapphire Placer Deposit, Buryatia, Russia." Minerals 12, no. 5 (April 20, 2022): 509. http://dx.doi.org/10.3390/min12050509.

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A new gem corundum occurrence has been discovered in the Naryn-Gol Creek placer of the Dzhida volcanic field (Russia). In this placer deposit, sapphire associates with large crystals of garnet, spinel, augite, olivine, enstatite, ilmenite, Ti-magnetite, and alkali feldspar. Such a combination of minerals is typical for the placer deposits associated with alkali basalts widely distributed in Southeastern Asia and Australia. We have also found sapphire crystals in phonotephrites of the nearby Cenozoic alkali-basalt paleovolcano Barun Khobol Pravyi, and in basalt sample and trachybasalt from the valley flood basalts. The chemical composition of sapphire is generally typical for ‘basalt’ corundum: it is rich in Fe, and depleted in Ti and Cr. The δ18O SMOW values of corundum and related megacrysts range from 4.6 to 6.8 ‰, thus corresponding to the isotopic signature of igneous rocks. Etched and corroded surfaces of sapphire and other megacrysts indicate that they are in non-equilibrium with their host alkali basalts. Volatile components, CO2 in particular, played a significant role during sapphire formation as gas inclusions reveal.

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32

Yarmolyuk, V. V., E. A. Kudryashova, and A. M. Kozlovsky. "Late stages in the evolution of the late Mesozoic East Mongolian volcanic areal: rock age and composition." Доклады Академии наук 487, no. 3 (August 17, 2019): 283–88. http://dx.doi.org/10.31857/s0869-56524873283-288.

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The Mandakh-Madal-Gobi (MMG) zone of alkali basalt magmatism has been delineated in the Late Mesozoic East Mongolian volcanic areal. It comprises clusters of igneous rock bodies and isolated stocks, domes, sills, laccoliths, dikes, and limited fragments of lava flows composed of tephrite, phono-tephrite, and trachybasalt. Two pulses of magmatism in the MMG zone have occurred in the Late Cretaceous (about 85 Ma) and Early Cenozoic (about 50 Ma). Recognition of this zone and deciphering of its formation history demonstrated that the development of the entire East Mongolian volcanic areal had the same regularities as those identified in other major regions of the Late Mesozoic Central Asia magmatic province. This indicates that the areal undoubtedly belongs to the latter. These facts support the conclusion that the correlation observed through the zone’s evolution between reduction in the volume of igneous products and the change in their composition towards the OIB was apparently determined by a decrease in the effect of thermal sublithospheric mantle melts upon a metasomatically enriched lithospheric mantle, leading to its gradual elimination from the magma sources.

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33

Zhu, Yongfeng, and Yoshihide Ogasawara. "Clinopyroxene phenocrysts (with green salite cores) in trachybasalts: implications for two magma chambers under the Kokchetav UHP massif, North Kazakhstan." Journal of Asian Earth Sciences 22, no. 5 (January 2004): 517–27. http://dx.doi.org/10.1016/s1367-9120(03)00091-9.

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34

Yu. Fridovsky, Valery, Kyunney Yu Yakovleva, Antonina E. Vernikovskaya, Valery A. Vernikovsky, Nikolay Yu Matushkin, Pavel I. Kadilnikov, and Nickolay V. Rodionov. "Geodynamic Emplacement Setting of Late Jurassic Dikes of the Yana–Kolyma Gold Belt, NE Folded Framing of the Siberian Craton: Geochemical, Petrologic, and U–Pb Zircon Data." Minerals 10, no. 11 (November 11, 2020): 1000. http://dx.doi.org/10.3390/min10111000.

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We present the results of geostructural, mineralogic–petrographic, geochemical, and U–Pb geochronological investigations of mafic, intermediate, and felsic igneous rocks from dikes in the Yana–Kolyma gold belt of the Verkhoyansk–Kolyma folded area (northeastern Asia). The dikes of the Vyun deposit and the Shumniy occurrence intruding Mesozoic terrigenous rocks of the Kular–Nera and Polousniy–Debin terranes were examined in detail. The dikes had diverse mineralogical and petrographic compositions including trachybasalts, andesites, trachyandesites, dacites, and granodiorites. The rocks showed significant similarities in distributions of REE, and their concentrations of most HFSEs were close to the intermediate ones between ocean islands basalts and enriched middle ocean ridge basalts. We propose that the subduction that was ongoing during the collision of the Kolyma–Omolon superterrane with Siberia led to melting in the asthenospheric wedge and in the lithosphere, which formed a mixed source for the dike systems from both an enriched and a depleted mantle source. The U–Pb SHRIMP-II dates obtained for the dikes corresponded to the Late Jurassic interval of 151–145 Ma. We present a geodynamic model for the northeastern margin of the Siberian Craton for the Tithonian age of the Late Jurassic.

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35

Naumov, V. B., M. V. Portnyagin, M. L. Tolstykh, and V. V. Yarmolyuk. "Chemical composition and crystallization conditions of trachybasalts from the Dzhida field, Southern Baikal volcanic area: Evidence from melt and fluid inclusions." Geochemistry International 44, no. 3 (March 2006): 286–95. http://dx.doi.org/10.1134/s0016702906030062.

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36

Peretyazhko, I. S., E. A. Savina, N. S. Karmanov, and Yu D. Shcherbakov. "Genesis of mugearites and benmoreites of Nemrut Volcano, eastern Turkey: Magma mixing and fractional crystallization of trachybasaltic melt." Petrology 23, no. 4 (July 2015): 376–403. http://dx.doi.org/10.1134/s0869591115030042.

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37

Pontesilli, Alessio, Matteo Masotta, Manuela Nazzari, Silvio Mollo, Pietro Armienti, Piergiorgio Scarlato, and Marco Brenna. "Crystallization kinetics of clinopyroxene and titanomagnetite growing from a trachybasaltic melt: New insights from isothermal time-series experiments." Chemical Geology 510 (April 2019): 113–29. http://dx.doi.org/10.1016/j.chemgeo.2019.02.015.

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38

Peretyazhko, I. S., E. A. Savina, and S. I. Dril'. "EARLY CRETACEOUS TRACHYBASALT-TRACHYTE-TRACHYRHYOLITIC VOLCANISM IN THE NYALGA BASIN (CENTRAL MONGOLIA): SOURCES AND EVOLUTION OF CONTINENTAL RIFT MAGMAS." Геология и геофизика 59, no. 12 (2018): 2101–28. http://dx.doi.org/10.15372/gig20181211.

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39

Wyers, G. Paul, and Michael Barton. "Geochemistry of a transitional ne-trachybasalt ? Q-trachyte lava series from Patmos (Dodecanesos), Greece: further evidence for fractionation, mixing and assimilation." Contributions to Mineralogy and Petrology 97, no. 2 (October 1987): 279–91. http://dx.doi.org/10.1007/bf00371246.

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40

Osika, Aleksandra, Małgorzata Wistuba, and Ireneusz Malik. "Relief evolution of landslide slopes in the Kamienne Mts (Central Sudetes, Poland) – analysis of a high-resolution DEM from airborne LiDAR." Contemporary Trends in Geoscience 7, no. 1 (June 1, 2018): 1–20. http://dx.doi.org/10.2478/ctg-2018-0001.

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Abstract The aim of the study is to reconstruct the development of landslide relief in the Kamienne Mountains (Central Sudetes, SW Poland) based on a DEM from LiDAR data. Analyses of relief and geological maps in ArcGIS 10.5 and of slope cross-sections in Surfer 14 allowed to distinguish different types of landslide relief, developed in latites and trachybasalts lying above claystones and mudstones. The types vary from small, poorly visible landslides to vast landslides with complex relief. They were interpreted as consecutive stages of geomorphic evolution of hillslope-valley topography of the study area. Two main schemes have been established which explain the development of landslide slopes in the Kamienne Mts: (1) upslope, from the base of the slope towards the mountain ridge and (2) downslope, beginning on the top of the mountain ridge. The direction of landslide development depends on the thickness of volcanic rocks in relation to underlying sedimentary rocks. When the latter appear only in the lowest part of the slope, landslides develop upslope. If sedimentary rocks dominate on the slope and volcanic rocks form only its uppermost part, landslides develop downslope. The results show that landsliding leads to significant modifications of relief of the study area, including complete degradation of mountain ridges.

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Barnes, Stephen J., David Paterson, Teresa Ubide, Louise E. Schoneveld, Chris Ryan, and Margaux Le Vaillant. "Imaging trace-element zoning in pyroxenes using synchrotron XRF mapping with the Maia detector array: Benefit of low-incident energy." American Mineralogist 105, no. 1 (January 1, 2020): 136–40. http://dx.doi.org/10.2138/am-2020-7228.

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Abstract Trace-element zoning in igneous phenocrysts and cumulus phases is an informative record of magmatic evolution. The advent of microbeam X-ray fluorescence (XRF) mapping has allowed rapid chemical imaging of samples at thin section to decimeter scale, revealing such zoning patterns. Mapping with synchrotron radiation using multidetector arrays has proved especially effective, allowing entire thin sections to be imaged at micrometer-scale resolution in a matter of hours. The resolution of subtle minor element zoning, particularly in first-row transition metals, is greatly enhanced in synchrotron X-ray fluorescence microscopy (XFM) images by scanning with input beam energy below the FeKα line. In the examples shown here, from a phenocryst rich trachybasalt from Mt Etna (Italy) and from a Ni-Cu-PGE ore-bearing intrusion at Norilsk (Siberia), the zoning patterns revealed in this way record aspects of the crystallization history that are not readily evident from XFM images collected using higher incident energies and that cannot be obtained at comparable spatial resolutions by any other methods within reasonable scan times. This approach has considerable potential as a geochemical tool for investigating magmatic processes and is also likely to be applicable in a wide variety of other fields.

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42

Winther, T. "Feldspar megacrysts and anorthosite xenolith-bearing dykes in the Narssarssuaq area, South Greenland." Rapport Grønlands Geologiske Undersøgelse 154 (January 1, 1992): 49–59. http://dx.doi.org/10.34194/rapggu.v154.8168.

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Numerous dyke intrusions are found in the Narssarssuaq area of the Gardar province, a Mid-Proterozoic intracontinental rift system. Ten to fifteen percent of these dykes, which range in composition from trachybasalt to phonolite and rhyolite, contain significant proportions of feldspar megacrysts and occasionally anorthosite xenoliths. Two groups of dykes are distinguished; the older group is more alkaline, richer in incompatible elements and contains more anorthosite xenoliths than the younger. It is probable that the main reason for the differences is variation in magma production through time and from one area to another. Chemical zonation in the dykes reflects compositional gradients in the feeding magma reservoirs; the magma reservoirs acting as open systems in which crystal fractionation was an important controlling process. The anorthosite xenoliths are not strictly cognate with their hosts, but were derived from comparable alkaline magmas with a composition roughly corresponding to the most primitive of the dykes. The plagioclase megacrysts were presumably formed at an early stage of the development of the magma chambers. Rb-Sr dating of one of the dykes from the older group of dykes gives an age of 1206 ± 20 Ma and an initial 87Sr/86Sr ratio of 0.7028 ± 0.0001 supporting a low degree of contamination with upper crustal Sr.

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43

Zhang, Ming, Paul Suddaby, Robert N. Thompson, and Michael A. Dungan. "The origins of contrasting zoning patterns in hyalophane from olivine leucitites, Northeast China." Mineralogical Magazine 57, no. 389 (December 1993): 565–73. http://dx.doi.org/10.1180/minmag.1993.057.389.01.

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AbstractOlivine (ol) leucitite lavas from Northeast China contain hyalophanes with contrasting Ba-zoning patterns. The hyalophanes occur: (1) in a magmatic inclusion (DZ2n), consisting of barian-titanian phlogopite + hyalophane + leucite + sodalite, and (2) as a mantle surrounding a sanidine megacryst (DZ19). Hyalophanes contain 4.6-20.2 mol.% celsian (Cn). The DZ2n hyalophane is normally zoned with respect to Ba (decreasing Ba toward rim), whereas the hyalophane mantle of megacryst DZ19 is reversely zoned. DZ2n probably crystallised from an extensively evolved (>80 wt.% crystallisation) potassic melt derived from a primitive magma chemically similar to the host, at relatively low temperatures and pressures (e.g. T-720°C P∼2 kbar). Competition with barian-titanian phlogopite for Ba, and limited Ba supply from the residual melt are the main cause for the normal Ba zonation. Sanidine megacryst DZ19 originated as a high P-T product (e.g. T > 950°C P > 15 kbar) of an evolved leucite (lc) basanite/trachybasalt genetically related to ol-leucitites. Subsequently, it was incorporated into the host ol-leucititic magma at which point it was partially resorbed and then mantled by hyalophane. An increase in KBaaf/liq values with decreasing temperature and pressure and cocrystallisation of the hyalophane mantle with Ba-free phases may have caused the unusual reverse zonation.

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Bars, Amarjargal, Khasmaral Togtokh, Laicheng Miao, Fochin Zhang, Munkhtsengel Baatar, and Chimedtseren Anand. "Geochemistry, geochronology, and tectonic setting of the Cretaceous volcanic rocks in east Mongolia." Геологийн асуудлууд 16 (February 23, 2023): 46–75. http://dx.doi.org/10.22353/.v16i1.2260.

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Late Mesozoic volcanic rocks in East Mongolia exhibit high-K calc-alkaline and shoshonitic series and display features of bimodal-like volcanic with a mafic and felsic members. The mafic member is composed mainly of trachybasalt and basaltic trachyandesite, with a minor amount of trachyandesite. The mafic rocks have elevated incompatible trace element concentrations and significantly negative Nb-Ta and Ti anomalies, features of typical subduction-related magmas, distinguished from OIBs. The mafic magmas have undergone fractional crystallization dominated by pyroxene and/or olivine and crustal contamination. The mafic magma was derived from low-degree partial melting of an enriched lithospheric mantle source that might have been metasomatized by subduction-derived fluids. The felsic member consists of trachydacite and rhyolite. The geochemical data indicate they produced from partial melting of a crustal source that is dominated by juvenile mafic rocks. Our new K-Ar dating and previous age data demonstrated that the late Mesozoic volcanism in East Mongolia took place during Late Jurassic-Early Cretaceous at between 156-99 Ma. The model of the arc‒back-arc extension possibly induced by slab roll-back of the westward (paleo) Pacific-subduction can explain the geodynamic setting and the eastward young trend of the late Mesozoic volcanism in East Mongolia and its adjacent NE China.

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Khubanov, V. B., T. T. Vrublevskaya, B. Ts Tsyrenov, and A. A. Tsygankov. "Formation of the trachybasalt–trachyte bimodal series of the Malo-Khamardaban volcanotectonic complex, southwestern Transbaikalia: Role of fractional crystallization and magma mixing." Petrology 23, no. 5 (September 2015): 451–79. http://dx.doi.org/10.1134/s0869591115040037.

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Di Fiore, Fabrizio, Alessandro Vona, Antonio Costa, Silvio Mollo, and Claudia Romano. "Quantifying the influence of cooling and shear rate on the disequilibrium rheology of a trachybasaltic melt from Mt. Etna." Earth and Planetary Science Letters 594 (September 2022): 117725. http://dx.doi.org/10.1016/j.epsl.2022.117725.

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Park, Keunsu, Sung Hi Choi, Moonsup Cho, and Der-Chuen Lee. "Evolution of the lithospheric mantle beneath Mt. Baekdu (Changbaishan): Constraints from geochemical and Sr–Nd–Hf isotopic studies on peridotite xenoliths in trachybasalt." Lithos 286-287 (August 2017): 330–44. http://dx.doi.org/10.1016/j.lithos.2017.06.011.

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Arakawa, Fumiyasu, David Gonzales, Nancy McMillan, and Molly Murphy. "Evaluation of trade and interaction between Chaco Canyon and Chaco outlier sites in the American Southwest by investigating trachybasalt temper in pottery sherds." Journal of Archaeological Science: Reports 6 (April 2016): 115–24. http://dx.doi.org/10.1016/j.jasrep.2016.01.035.

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Peretyazhko, Igor S., and Elena A. Savina. "Chemistry and Crystallization Conditions of Minerals in Metasomatized Oceanic Lithosphere and Basaltic Rocks of Govorov Guyot, Magellan Seamounts, Pacific Ocean." Minerals 12, no. 10 (October 16, 2022): 1305. http://dx.doi.org/10.3390/min12101305.

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Studies have provided first detailed data on the chemistry of rock-forming, minor, and accessory minerals of Govorov Guyot volcanic rocks (basalts, trachybasalts, basaltic trachyandesites, and trachyandesites). Some basalt samples bear pargasitic amphibole and clinopyroxene xenocrysts, mantle vein fragments in xenoliths, as well as wehrlite xenoliths, which are remnants of metasomatized oceanic lithosphere. Amphiboles make up a continuous series from pargasite –Mg-hastingsite in wehrlite xenoliths and xenocrysts to Mg-hastingsite – kaersutite end-members in phenocrysts and microlites of basaltic rocks. The discussed issues include the trace element chemistry of Ti-amphibole and clinopyroxene phenocrysts; fractionation of OIB melts; and P-T equilibration of minerals during the formation of mantle and basaltic rocks. Pargasitic amphibole may have crystallized at P-T conditions (2.5–0.6 GPa, 1170–980 °C) corresponding to the spinel facies of peridotite at different depths (73–21 km) in hydrous (6.0–4.5 wt % H2O) silicate mafic melts that percolated through peridotites of the oceanic lithosphere. Ti-amphibole in basaltic rocks crystallized at 1.2–0.4 GPa (40–15 km), and 1060–910 °C from melts containing 8.6–2.6 wt % H2O. As the high-temperature (~1100 °C) basaltic magmas reached chambers at the oceanic crust level (7 to 3 km), the Ti-bearing amphiboles of xenocrysts and phenocrysts became replaced by Ti-magnetite- and/or rhönite-bearing mineral assemblages.

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Mollo, S., J. D. Blundy, P. Giacomoni, M. Nazzari, P. Scarlato, M. Coltorti, A. Langone, and D. Andronico. "Clinopyroxene-melt element partitioning during interaction between trachybasaltic magma and siliceous crust: Clues from quartzite enclaves at Mt. Etna volcano." Lithos 284-285 (July 2017): 447–61. http://dx.doi.org/10.1016/j.lithos.2017.05.003.

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Journal articles on the topic 'Trachybasalte'

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